The present invention relates to a visual information processing apparatus, and more specifically to an apparatus which processes visual information to detect the change in image with the lapse of time and to recognize objects in the image.
Apparatus which picks up a particular visual field by a TV camera and which automatically discriminates whether any change has developed in the image or in which region in the visual field the change in image has developed, can be usefully employed for an automatic detector which detects the number of customers, for example, in an elevator hall or for a group control system of elevators using the detector.
The most fundamental system for detecting the change in image consists of comparing the image data which corresponds to the background image that has been stored beforehand with the image data that is produced in a raster-scanning manner from a video device, to detect the difference.
However, the amount of digitized data covering the whole image as picked up by the TV camera is so great that comparison of the two images by directly storing them requires large apparatus for storing the image data, and further requires extremely high speed of data processing operation to deal with the data, resulting in expensive and bulky apparatus.
Furthermore, even when the same subject is being picked up, the image data obtained through the TV camera easily undergoes variation depending upon the intensity of light which illuminates the subject or depending upon the direction from which the subject is illuminated. Accordingly, when the two pictures are directly compared relying upon the individual image data, the data processing apparatus often erroneously renders the decision even when the same subject is being picked up.
To cope with the above-mentioned problem, the applicant of the present invention has previously proposed a visual information processing apparatus in which the whole image screen was divided into a plurality of blocks E.sub.00 to E.sub.mn, and the image corresponding to the background that had been stored beforehand was compared with the input image for each of the blocks, as has been disclosed in U.S. Pat. No. 3,936,800, Japanese Patent Application No. 139667/73 (Japanese Patent Laid-Open No. 93059/75), and Japanese Patent Application No. 153142/78 which corresponds to U.S. Pat. No. 4,254,400.
In this case, the individual blocks consist of a plurality of picture elements, picture element information is processed for each of the blocks along with the raster scanning, and the data are calculated having therein features which are in line with the direction of total brightness of the blocks or in line with the degree of brightness of the blocks to compress the amount of data that is to be compared with the background. With regard to the image that represents the background, the features are coded for each of the blocks in the same manner as mentioned above, and the data is stored in the memory device.
According to the system of the above-mentioned prior applications, blocks to be processed are specified for every video frame, and input image is compared with the background image by utilizing a vacant time during the raster scanning. Therefore, it is allowed, for every several frames in which the whole data processing is finished, to know the total number of blocks in which change has taken place or to know the distribution of changes in the video field, thereby to automatically detect, for example, the number of customers relying upon the above information.
The visual information processing apparatus based upon the abovementioned system can be extensively applied to a variety of industrial fields such as counting of articles in the steps of production, monitoring of residual amount, counting of blood cells from the microimage, detection of intruders in the safeguard system, and the like. The visual information processing apparatus can also be applied not only to live video signals produced by the TV cameras, but also to video signals that are read out from a memory in a manner of raster scanning.